PROCESS OF PREPARATION OF EMULSIFIER-FREE RUBBER LATICES

1. Process for the production of an emulsifierfree rubber latex from 1 to 6 parts by weight of methacrylic acid and 94 to 99 parts by weight of a mixture of 10 to 90 parts by weight of one or more acyclic conjugated dienes containing 4 to 9 carbon atoms and 10 to 90 parts by weight of one or more arylvinyl monomers containing 8 to 12 carbon atoms and/or (meth)acrylonitrile, the quantity of (meth)acrylonitrile being at most 50 parts by weight, characterized, in that a) an aqueous emulsion is prepared by adding at least one part of methacrylic acid, one part of diene and other monomers to water, b) polymerisation is initiated by adding an aqueous basic solution of a peroxodisulphate, which contains such a quantity of organic or inorganic bases that the polymerisation takes place at a pH of between 3.5 and 7, c) polymerisation is carried out in a first stage at a pH value of between 3.5 and 7 and a temperature above 70 degrees C until at least 50 % of the monomers have been converted, d) the remainder of the monomers and more aqueous basic peroxodisulphate solution, which contains such a quantity of organic or inorganic bases that the polymerisation takes place at a pH of between 3.5 and 7, are added in one or more further stages, e) the polymerisation is continued at a pH value of 3.5 to 7 and at above 70 degrees C until at least 50 % of the monomers have, in each case, been converted and, in the final stage, until 85 to 100 % of the monomers have been converted.